[BUG] filtergraph Constrains Maximum mixing-up when saving a patch

To reproduce:
in filtergraph.maxhelp :
-> in the filtergraph inspector, go to Constrains MAXIMUM Frequency/Amplitude/ or even Q : set it to "" using delete key
-> save the patch
-> open it again
-> now you have Constrains MINIMUM set to and the number that was in the MINIMUM is now in the MAXIMUM…